As is known, various types of packing materials have been used to insulate articles being transported in shipping containers against the danger of damage from vibration and impact forces. In particular, it has been known to use resilient thermoplastic elements for the packing materials. In many cases, these elements have been produced in shapes to provide not only a cushioning effect for the article being shipped but also a nesting relation or interlocking arrangement with each other to prevent migration of the packaged article during the course of shipment.
Generally, when an article is to be packaged, an empty carton is first opened and a mass of elements is poured from a supply hopper or other container into the shipping carton to fill the carton part way. Thereafter, the article is placed in the carton and a further mass of elements is poured from the supply hopper or container into the carton to a point of overfilled. Next, the carton is closed in a manner such that the overfilled elements are pressed down into the carton. This causes the various elements to press together in an interlocking manner or a nesting manner depending on the shapes of the elements.
Heretofore, in order to manufacture resilient thermal packing elements, it has been know to extrude a heat-plastified mass of thermoplastic material containing an expanding agent through an orifice to form a rod which is then severed at longitudinal increments into discrete elements. In some cases, it has also been known to cool the rod after extrusion and prior to cutting. In such cases, the subsequently cut elements are of a latent foaming or expandable nature. That is, the elements can be subjected to heat at a later time to cause an expansion of the elements due to the expanding agent incorporated therein. Such latent foaming elements can be shipped in bulk to the ultimate user and thereafter expanded under heat into a useable state. Where the shapes of the element permit, the foamed elements can be poured from hoppers or the like into individual shipping containers.
As is known, resilient thermoplastic loose fill packaging elements have been manufactured in various shapes, such as E-shapes, C-shapes, S-shapes, U-shapes and various hooked shapes, such as described in U.S. Pat. No. 4,514,453. Because of the interlocking or nesting characteristics of C-shaped and U-shaped loose fill elements, these elements may interlock or nest while in a hopper so that jamming of the hopper occurs that prevents free flow of the elements out of the hopper. Also, these elements by interlocking may occupy less volume in a shipping container particularly due to settling. This, in turn, may give the user a false impression that there is a short-weight condition.
Accordingly, it is an object of the invention to provide a loose fill packing element which occupies a maximum space with a minimum of weight.
It is another object of the invention to provide loose fill packing elements which do not interlock or nest with each other.
It is another object of the invention to provide a packaging material made of packing elements that will not settle to any appreciable extent during shipment in containers.
It is another object of the invention to provide an apparatus for making a packing element of unique shape.